— Roaring rivers —
On the prehistory of rivers
Do rivers change their course through time?
Yes, they do. Almost all rivers change course several times throughout their lifetime. Do we know how and why?
For many rivers, we know. But not for all of them. But you are lucky. Because the writer of this website is a geologist who is specialized in rivers. And in their natural history in particular. I've written a lot about rivers and their evolution, for work and research. But now I want to do this for a wider audience and especially for science dummies. I think it's fascinating. Why do I think that?
The history of a river is closely linked to past climate change, the former biotopes, the deserts, the seas, the migration of fauna and flora... Everything is interconnected. And not just esoterically. The interconnectedness is the basis of what specialists call Earth systems science. Hell yeah!
We can all name some of the large rivers of the world. The Amazon, Nile, Congo, and Indus are just a few. And the Limpopo, Darling, and Mackenzie? Oops, we're going too fast. Rivers seem to have been there forever. And most of them have, at least during human history.
The rise and fall of civilizations were dictated by the ebb and flood of rivers. Ancient Egypt and the Nile are inextricably linked, not to mention Mesopotamia, which means land between the rivers. And don't let me explain the importance of the Indus on the Indus Valley Civilization. Moreover, large river basins are the last refuge of uncontacted or isolated peoples.
There is indeed a lot to tell on what happens on and along the world's large rivers.
But less is known - unless you dive in the academic literature - on the more ancient history of rivers. And they changed all the time.
Can you imagine that the Amazon is actually a super young river? Now it flows across the South American continent all the way to the east, but maybe only three million years ago, it flowed in the opposite direction. Geologically speaking that's only a second ago. Did you know that not so long ago, the Sahara was dotted by many lakes and wetlands? And that maybe the Nile was not the only 'corridor' for early humans to leave Africa, as in one of the Out of Africa hypotheses? In this series, you will learn more about the prehistory of rivers.
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